Safety device for elevators



{No Model.)

S. P. KAY. SAFETY DEVICE FOR ELEVATORS.

Patented Jan. 8, 1895.

agu'rdefrueryhgze/mb viii/7y Cd L'aZqu,

UNITED STATES PATENT EEICE.

SAMUEL P. KAY, OF ROCHESTER, NEW YORK.

SAFETY DEVICE FOR ELEVATORS.

SPECIFICATION forming part of Letters Patent No. 532,158, dated January 8, 1895.

Application filed August 1'7 1894. Serial No. 520,642- (No model.)

To all whom it may concern:

Be it known that I, SAMUEL P. KAY, a citizen of the United States, and a resident of the city of Rochester, in the county of Monroe and State of New York, have invented a certain new and useful Safety Device for Elevators, of which the following is a specification, reference being had to the accompanying drawings, in which-e Figure l is a front elevation of a portion of an elevator car having my safety device attached thereto. Fig. 2- is a top plan view of the mechanism of my device, parts being removed to economize space in the drawings. Fig. 3 is a side elevation of-one end of my device, parts being removed to exhibit construction. Fig. 4. is a side elevation of one of the clamping jaws. Fig. 5 is an end elevation of one of said jaws as seen from the smaller end. Fig. 6 is an end elevation of the end of one of the operating levers, and Fig. 7 is a side elevation of Fig. 6.

The object of my invention is to provide a positively operated device for stopping elevator cars in case of breakage of the cable, or failure of the hoisting mechanism, or in any case when the hoisting cable becomes slack; and my invention consists in the mechanism hereinafter described and claimed.

In the drawings X is the elevator car which is hung from transverse supporting beams Y and Z by connecting bars W W.

A A are fixed vertical guide ways in the elevator well, and placed opposite the ends of the supporting beams Y, Z.

B B are gripping or clamping jaws placed between the ends of the supporting beams and having faces traveling close to the guide ways,but normally not in contact therewith. The jaws B B act as guides for the car, when not in operation for stopping it. Each of the gripping jaws B B is provided with a rib b, preferably, for leverage, nearer to the end I) than to the end I), and which rests in a slight groove in the adjacent supporting beam, and forms the fulcrum upon which the jaw oscillates or rocks. Through a perforation b in each jaw, there passes a bolt b to hold it in place, and this bolt passes also through the supporting beams with the head and nut of the bolt on the outside of the beams. Each beam is therefore a fixed support for the clamping jaw which is fulcrumed against it. On the end I) of each jaw, opposite to the end 1) thereof, is a projecting lug b Between the lugs b is an operating mechanism which serves to separate the jaws at the ends 17 and to. clamp the ways A between the ends b b. Springs b are arranged to keep the ends 6 as near together as the other parts will admit. Between the lug b and the fulcrum b of each jaw, the jaw is perforated, as at 22 for the free passage of a bolt c. The bolt 0 passes also through the supporting beams. Upon the bolt 0' is a ring cto which is fastened a lever C. The bolt 0' passes through a perforation in the ring and the ring revolves upon the bolt as an axis. The ring 0 is, on its opposite sides, cut away to form a cam or double wedge 0 which rests between the lugs 12 of the jaws B. This wedge I prefer to make parabolic in form, or of a grad ually decreasing lead, so that if the wedge moves uniformly, it will at first spread the jaws B B rapidly, taking up all the slack between the jaws and the ways, and then the spreading will decrease, as thewedge enters farther between the jaws, with less rapidity but with increasing power. .This wedge is actually curved, in order that the action shall be continuous as the ring 0 turns upon the bolt 0. As the lever 0 moves upward, as shown by the arrow in Fig. 3, the wedge 0 moves between the lugs b of the jaws B and separates them, with the effect of gripping 8 the ways A; A slight depression 0 is made on each side of the ring at the beginning point of each of the wedges 0 The lugs b fit into these depressions and tend to lock the parts lightly together so as to be normally go inoperative as a clamping device, butso as to be easily disengaged. One of these clamping devices is placed at each end of the sup porting beams to clamp each of the two usual guide ways of the elevator shaft. The levers O extend to the middle of the supporting beams and are preferably curved, so as to'forln off-sets at the ends as shown most clearly in Fig. 2. To the end of each lever is fastened a cable E, running to the too counterweight E over the sheaves H H at the top of the elevator well. Cables F to the hoisting engine, pass around pulleys D D, preferably grooved, and journaled on pins or bolts d passing through the supporting beams, and the cables, after passing around said pulleys, are fastened to the levers O at a suitable distance from the ends of such le- Vers. A bolt G extending across between the two supporting beams, is so placed as to serve as a stop for the motion of the levers C. There is in my device a system of compound levers to cause the ends I) b of the jaws to grip the ways:to wit, the lever O, the wedge 0 and the leverage of the jaws B B.

The operation of my device is as follows: In the ordinary operation of the car, the hoisting cable F pulls the lever O downward against the stop G and the weight of the car keeps theparts in this position. Other hoisting cables F are ordinarily used in addition to those which are attached to the levers 0, but the hoisting cables F, which are attached to the levers O, are, with the parts around which they pass or to which they are fastened, normally strong enough to support the car and its proper load. If an accident should happen to the hoisting engine by which the cables were slackened, or if the cables F F or either of them, should break, or if the car should be subjected to a sudden stoppage, and the re bound after the stoppage should slacken the hoisting cables, in any one of these cases if the cable F slackens and permits the lever G to be raised away from the pin G, the counterweight E falls and draws the end of the lever C upward, as shown in dotted lines in Fig. 3, thus turning the ring 0 and forcing the wedge 0 between the jaws B, which causes the jaws to grasp and hold the ways A, and the car stops. The faster the car drops, the stronger is the pull upon the counterweight cable E and the farther the double cam or wedge c separates the ends 17 of the jaws B and the tighter is the grasp of the jaws upon the ways. By the parabolic form of the cam or wedge 0 the pressure of the gripping jaws B B will, on only a slight pull on the lever 0, cause the lever to return to its normal position and release the clamping action of the jaws upon the Ways; while a longer pull on the lever will bring the sides of the wedge or cam into operationwhere they are more nearly parallel, and the wedge or cam is locked in a clamping position. Repeated trials of this device have demonstrated that ,the gripping action of these jaws is positive and certain, and checks even a heavily loaded car before it can acquire dangerous headway, and upon a very slight slackening of the hoisting cables; and further that, when the jaws are brought into action by reason of a sudden stoppage and a rebound of the car, as soon as the car comes to rest, and the normal balance of the device is resumed, the jaws B B are automatically released from the ways A by the pull of the cables F on the levers O, and the car may be operated without further delay.

A speed governor may be added to the car operating mechanism in the usual way and the cablesE may be attached thereto so that when the speed of the car is too great, the levers C will be actuated to bring the clamping mechanism into operation. In this case the sheaves H represent the governor.

I believe that I am the first to make use of a cam or wedge, or an equivalent therefor, of parabolic form or of any differential lead, for

positively operating a pair of jaws arranged.

to clamp a fixed gui$e way in an elevator safety device. The prior cam or screw devices, known to me in this art, all have a uniform lead, and have the disadvantage, as'compared with mine, of using no more power to produce the clamping action after the elevator acquires speed and momentum in its fall than when it starts. In fact, as the levers 0 rise under the pull of the counterweight cable, the power of the counterweight, in operating the mechanism, decreases, on account of the change of angle of the lever with reference to the line of pull; but my triple compound leverage, or my wedge device of decreasing or diffential lead, each permits increasing force to be produced withdecreasing leverage and insures an increasing clamping power as the speed or momentum of the elevator increases in falling. If a lever were used with some simple mechanism of uniform lead or without a compound leverage, the power ofthe lever would decrease as it rose from its stop and the clamping would be less forcible as it became more necessary.

In elevators of very high speed, this device is superior in operation to devices operated by means of a screw or rack, or to devices in which teeth are forced into the ways, inasmuch as the great speed of the elevators will often cause such devices to operate when it is not desirable that they should do so. In most of the devices in which screws and other mechanisms, such as mentioned, are used, the clamping action of the parts is of such force that they are liable to be broken when the accident occurs for which the safety device is devised, and generally the parts are so jammed and so tightly forced into position that it becomes a matter of great difficulty to disengage the safety device in order to permit the car to resume operation. As hereinbefore stated, my device obviates these obj ec' tions; it is certain in operation; it is automatically released when it is. safe to do so after being brought into action; it is easily disengaged for the purpose of resuming the operation of the car; it is simple and cheap to manufacture; it is practicable to use upon elevators of the highest speed for carrying passengers; it does not necessitate the use of a governor for regulating the speed of the car; and it has no long bearing surfaces or other parts to rust or deteriorate from disuse and accumulated dirt and dust do not prevent its action, as it clears itself.

Under suitable circumstances, I connect the cable E with a speed governor as de- IOO scribed, instead of connecting it with the counterweight. In this case the counterweight is independently connected to the car. The essential function of the cable E in my device, is to keep or put a tension on the mechanism for operating the wedge 0 when the hoisting cable breaks or becomes too slack. When the hoisting cable breaks, it, of course, immediately becomes too slack. 7

It is obvious that my invention may be modified in details without departing from the principle thereof or using any devices but such as are mechanical equivalents for the elements set forth in the claims.

What I claim is 1. The combination, with the elevator car and the fixed guide ways, of a pair of clamp 'ing jaws for each guide way,'each jaw being fulcrumed against a suitable fixed support upon the car, a wedge device for operating the clamping jaws to clamp the ways, a hoisting cable, a lever adapted to operate said wedge device, the wedge device and the lever being so constructed and connected that as the power of the lever decreases, the power of the wedge increases, means, as a connection between the hoisting cable and the lever, to hold the wedge device normally out of operation, and means, as a cable connected to said lever, for bringing the lever into operation when the hoisting cable becomes too slack.

2. The combination, with the elevator car and the fixed guide ways, of clamping jaws set in suitable supports on the car, a wedge device of decreasing lead for operating the clamping jaws to clamp the ways rapidly at first but more slowly thereafter, a hoisting cable, means? as a connection between the hoisting cable and the wedge device, to hold the latter out of operation, and a cable attached to said wedge device for bringing the same into operation when the hoisting cable slackens.

3. The combination, with the elevator car and the fixed guide ways, of fixed supports on said elevator, jaws arranged in said supports to clamp said ways, adifterential wedge device for actuating said jaws with increasing power, a lever for operating 'said wedge 50 device, a hoisting cable, and a cable connected to said lever to operate the wedge device when the hoisting cable becomes too slack.

at. The combination, with the elevator car and the fixed guide ways, of non-movable supporting beams, a pair of oscillatory clamping jaws at each end of said beams, arranged to clamp said ways, each jaw being fulcrumed against one of said beams, a diiferential wedge device for actuating each pair of jaws, a lever for operating each wedge device, a hoisting cable, and a counterweight cable connected with said lever to operate the wedge device when the hoisting cable becomes too slack.

5. The combination,-with the elevator car and the fixed guide ways, of a pair of clampingjaws arranged at each end of said beams to clamp said ways, a Wedge arranged to move between said jaws and to clamp the same against said ways, said cam or wedge being of decreasing lead whereby it operates the jaws rapidly at first and then more slowly but with increasing power, and means of operating said wedge when the hoisting cable breaks or becomes too slack.

6. The combination, with the elevator car, the hoisting cable and the fixed guide ways, of a pair of clamping jaws arranged at each end of said beams to clamp said ways, a ring having a cam or curved wedge thereon arranged to turnbetween said jaws and to clamp the same against said ways, said cam or wedge being of decreasing lead whereby it operates the jaws rapidly at first and then more slowly but with increasing power,and means of operating said ring when the hoisting cable breaks or becomes too slack.

7. The combination, with the elevator car and the fixed guide ways, of oscillatory clamping'jaws set betweenfixed supports upon the car, a lever provided with a rotary, differential wedge device for operating the clamping jaws, a hoisting cable, and a counterweight cable connected to said lever and adapted to operate the said lever in opposite directions.

8. The combination, with the elevator car and the fixed guide ways, of oscillatory clamping jaws fulcrumed against and between fixed supports upon the car, a lever bearing a wedge device for operating the clamping jaws, and a hoisting cable and a counterweight cable attached, one to one side and the other to the other side of said lever and operating the said lever in opposite directions, said clamping mechanism consisting of opposite jaws having fulcrums at unequal distances from their ends and operated directly by said wedge device to separate the long leverage ends of the jaws and to clamp the ways between the short leverage ends thereof, whereby a triple compound leverage is produced by the lever, the

wedge and the jaws.

9. The combination, with the elevator car and the fixed guide ways, of fulcrumed clamping jaws attached to the car, a pivoted lever bearing a cam or wedge device of decreasing lead for operating the clamping jaws, a hoisting cable and a cable to the counterweight attached, one to the one side and one to the other side of said lever, and operating the said lever in opposite directions.

10. The combination, with the elevator car and the guide ways, of fulcrumed jaws having fixed supports attached to the car, a pivoted lever bearing a parabolic wedge device for operating the clamping jaws, a hoisting cable and a cable to the counterweight attached, one to one side and one to the other side of said lever, and operating the said lever respectively in opposite directions; said clamping mechanism consisting of opposite jaws having suitable fulcrums and operated by said wedge to separate the long leverage ends of the jaws and to clamp the ways between the short leverage ends thereof.

11. The combination, with the elevatorcar and the fixed guide ways, of a clamp on the car for a guide way, and mechanism for operating said clamp speedily at first and then more slowly but with increasing power, and the hoisting and counterweight cables oppositely connected to said mechanism whereby to operate the same when the hoisting cable becomes too slack. I

12. The combination, with the elevator car, the clamp thereon, the fixed guide way with which said clamp co-operates, of the lever having the wedge device of decreasing lead engaging the clamp, and the hoisting and counterweight cables connected to opposite sides of said lever.

13. The combination, with the elevator car, the clamp thereon and the stationary guide ways with which the clamp co-operates, of

the lever having the wedge device of decreasing lead engaging the clamp, the hoisting and counterweight cables connected to opposite sides of said lever and the stop against which the lever is held by the hoisting cable.

14. The combination, with the elevator car, the hoisting cable and the fixed guide ways, of the clamp on the car for a guide way, mechanism for operating said clamp consisting of a cam or wedge of differential lead, and the hoisting and counterweight cables attached to said mechanism and arranged to operate the cam or wedge when the hoisting cable breaks or becomes too slack. V

15. The combination with an elevator car, a hoisting cable and fixed guide ways, of a clamping device on said car for a guide way, a wedge device of parabolic form for operating said clamping device with decreasing speed but with increasing power, and means for operating said wedge device when'the hoisting cable breaks or becomes too slack.

, SAMUEL P. KAY.

Witnesses:

M. H. BRIGGS, CHAS. A. EDGERTON. 

